The invention relates to the treatment and prevention of amyotrophic lateral sclerosis (ALS) by the administration of estrogen. Pretreatment with an estrogen compound, for example, with the estrogenic isoflavone, genistein, prevents pathologic conditions associated with ALS and delays disease onset in individuals at high risk for ALS.
Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig""s disease, is a progressive, fatal neurodegenerative disorder involving the motor neurons of the cortex, brain stem, and spinal cord (Hirano, A., 1996, Neurology 47 (Suppl. 2), S63-S66). It is a degenerative disease of upper and lower motor neurons that produces progressive weakness of voluntary muscles, with eventual death. The onset of disease is usually in the fourth or fifth decade of life, and affected individuals succumb within 2 to 5 years of disease onset. ALS occurs in both sporadic and familial forms. About 10% of all ALS patients are familial cases, of which 20% have mutations in the superoxide dismutase 1 (SOD1) gene (formerly known as Cu,Zn-SOD), suggesting that an abnormally functioning Cu,Zn-SOD enzyme may play a pivotal role in the pathogenesis and progression of familial amyotrophic lateral sclerosis (FALS) (Rosen et al., 1993, Nature 362: 59; Siddique et al., 1991, N. Engl. J. Med. 324:1381).
More than 50 point mutations of the human SOD1 gene have been found in patients with FALS. Most of the mutations occur at regions involved in the subunit folding exposing the active site to the outside, leading to increased hydroxyl radical generation. It is believed that the increased generation of oxygen free radicals, especially hydroxyl radicals, by mutant SOD1, to be the initiating factor that results in the sequence of events leading to motor neuron death in FALS. This hypothesis is supported by recent reports that transfection of neuronal precursor cells with mutant SOD1 results in increased production of hydroxyl radicals and enhanced rate of cell death by apoptosis (Liu et al., 1999, Radiat. Res. 151:133).
The incidence of ALS in males is higher than in females (Reed and Brody, 1975, Am. J. Epidemiol. 101:287; Yoshida et al., 1986, Neuroepidemiology 5:61), indicating a sexual dimorphic etiology. It is known that estrogen therapy can produce beneficial effects for a variety of diseases, however, estrogen has not previously been suggested as useful in the treatment of ALS.
Estrogen treatment reportedly lowers the incidence of cardiovascular diseases and stroke mortality 70% and 36%, respectively (Stampfer et al., 1991, N. Engl. J. Med., 325: 756-762; Paganini-Hill et al., 1988, Br Med J, 297: 519-522). Physiological events, such as improved cerebrovascular blood flow, as well as cellular events, such as attenuation of neuronal cell death from glutamate toxicity and oxidative stress, are all involved in the neuroprotective activity of estrogen.
Phytoestrogens are non-steroidal plant compounds that have estrogenic activity in humans and animals. Genistein is a phytoestrogen exhibiting weak estrogen activity both in vitro and in vivo (Santel et al, 1997, J. Nutr, 127:263-269; Hilakivi-Clarke et al., 1998, Oncol Rep, 5: 609-616; Zava et al., 1997, Environ Health Perspect, 105(Suppl. 3): 637-645). In vitro, genistein binds to the estrogen receptor and induces estrogen-regulated end products (Zava et al., 1997, supra). However, genistein, has also been shown to exhibit pleiotropic biologic activities including antioxidant activity (Ruiz-Larrea et.al., 1997 Free Rad. Res. 26:63); inhibition of tyrosine kinase activity (Uckun et.al., 1995, Science 267:886) and protective activity against radiation induced apoptotic cell death (Uckun et.al., 1992, PNAS USA 89:9005).
Despite having been studied for over 100 years, the etiology of ALS is still largely unknown with no clearly effective treatment or method of prevention. Methods and compositions that prevent or ameliorate the neurologic damage indicative of ALS are needed. Accordingly, there is a need for a method or composition that prevents or delays onset of pathologic conditions related to ALS. In the present invention, phytoestrogens such as the isoflavone genistein, are demonstrated to be effective as a neuroprotective compounds which can delay onset of ALS and pathological symptoms associated with this disease.
The present invention provides methods for preventing and/or delaying symptoms, or treating symptoms relating to amyotrophic lateral sclerosis (ALS). More particularly, the invention provides estrogens, particularly phytoestrogens, and preferably estrogenic flavonoid compounds having one or more hydroxylated aromatic rings, for the treatment of ALS. Preferred estrogens include genistein and effective analogs of genistein, coumestrol, zeanoloval, 4-(4xe2x80x2-hydroxylphenyl)-amino-6,7-dimethoxyquinazoline (P131) and 2,4,4xe2x80x2-trihydroxy deoxybenzoin (DDE-17) for administration to a subject for the prevention and/or treatment of ALS
Preferably, the estrogen is administered to a patient before the onset of ALS. Administration of the estrogen to the patient, can be, for example, systemically, or locally into a tissue.
A patient to be treated by the method of the invention is one determined to be susceptible to ALS, one exhibiting a symptom associated with ALS, or one diagnosed as suffering from ALS. Patients susceptible to ALS include patients at risk of developing ALS. These would include, for example, patients with a family history or predisposition to developing ALS, and the like. Indications that a patient is susceptible to ALS include those individuals testing positive for molecular markers indicative of or associated with ALS. Such markers include, for example, any one of the known mutations in the SOD1 gene (Deng et al., 1993, Science, 261: 1047-1051).
Accordingly, one embodiment of the present invention includes a method for preventing onset of ALS, including the step of administering to a subject, prior to the onset of ALS, an effective amount of an estrogen, such as coumestrol, zearolonal, or genistein. Preferred is the administration of a hydroxy-substituted estrogenic isoflavone having the general formula I shown below. The invention also includes prevention of disease progression by administering such a compound; and also use of estrogens for the treatment of ALS disease symptoms. 
R is NH2, halo, C1-C6 alkyl, or ORxe2x80x2 and n is 1 to 4, wherein at least one R is ORxe2x80x2, and Rxe2x80x2 is H, C1-C6 alkyl, or a sugar moiety. (It is common for a sugar moiety to bind the flavone via reaction with the flavone""s hydroxyl groups.) One or both of the rings, A and B, each comprise one or more hydroxyl groups (R). Preferred are phytoestrogens and their active estrogenic derivatives. Most preferred is the estrogenic isoflavone, genistein, shown below. 
The above summary of the present invention is not intended to describe each disclosed embodiment or every implementation of the present invention. The Figures and the detailed description which follow more particularly exemplify these embodiments.